Conventionally, so-called air-sol type atomizer has been widely used, in which a pressurized propellant gas is used. The gas has been found, however, harmful to human bodies. In addition, there is a danger that the wasted container may explode due to the residual propellant gas.
For these reasons, so-called manual type small sized atomizers are now under reconsideration.
However, in conventional atomizers of this type, it is difficult to obtain a sufficient atomizing pressure, especially at the beginning of the atomization, so that fine particles of atomized content are not available.
In order to overcome this problem, the present Applicant has proposed a so-called accumulator type atomizer, in U.S. Pat. No. 3,908,870. This type of atomizer has a discharge valve which is forced to be closed, even when a atomizing head is depressed, until a sufficient pressure is established within the cylinder chamber. In other words, the discharge valve is allowed to open only after a sufficient pressure has been established to allow the atomization.
Although this accumulator type atomizer provides a solution to the aforementioned problem, another problem is caused that a considerably large force is required for depressing the atomizer head, resisting the forcible closing force on the discharge valve.
Also, in the atomizer of the other type than the accumulator type, a large depressing force is required for depressing the atomizer head, when the amount of spray at one time is large.
The present invention is aiming at providing a cap which is most advantageously used for these atomizers which require a large depressing force on the atomizer head, especially for accumulator type ones.